Cleaner Fish Welfare in Salmon Aquaculture

The welfare challenges facing cleaner fish used to control sea lice in salmon farming and emerging standards for their protection.

Key Facts

Cleaner fish — primarily wrasse species and lumpfish — are used in salmon farms to eat sea lice from salmon
Billions of cleaner fish are now used annually in Norwegian salmon farming as an alternative to chemical treatments
Wrasse are caught wild from coastal reefs or farmed, with wild capture raising significant sustainability concerns
Cleaner fish have high mortality rates in salmon farms from aggression by salmon, cold temperatures, and disease
Lumpfish bred in hatcheries perform better in cold water farms than wrasse, which are more temperature-sensitive
The welfare of cleaner fish has received little attention despite their cognitive complexity and suffering potential

Welfare Considerations

Cleaner fish welfare represents a newly recognized but significant issue in sustainable aquaculture. The rapid growth in cleaner fish deployment — driven by pressure to reduce chemical sea lice treatments — has created a situation where billions of fish are placed in potentially harmful conditions with minimal welfare consideration. Wrasse, in particular, are complex fish with established home ranges on reef habitat, territorial behavior, and cognitive abilities that raise serious questions about their welfare in salmon pen environments. High mortality rates among cleaner fish in farms reflect both the welfare problems of their confinement and the production challenges for the industry. The development of welfare standards for cleaner fish — specifying minimum stocking densities, refuge provision, temperature suitability, and handling requirements — represents an urgent and currently underaddressed welfare frontier in aquaculture.

What You Can Do

Support development of specific welfare standards for cleaner fish in aquaculture certification schemes
Ask about cleaner fish welfare practices when evaluating certified salmon products
Advocate for research investment into cleaner fish welfare needs and biology
Support transition to hatchery-produced cleaner fish over wild capture to reduce reef ecosystem impacts
Engage with aquaculture sustainability debates that include cleaner fish welfare as a genuine consideration